Heat-responsive controls



April 9, 1957 H.A.HCHTER HEAT-RESPONSIVE CONTROLS Filed May 17, 1954 INVENTOR. HENRY A. FIGHTER.

2,788,417 HEAT-RESPONSIVE CONTROLS Henry A. Fichter, St. Louis, Mo. Application May 17, 1954, Serial No. 430,131 Claims. (Cl. 200-142) This invention relates to controls generally, for throwing selected mechanisms out of operation under certain conditions, and more especially to such a control that will safeguard mechanisms and units that are being heated, the control acting to shut off further feed to such mechanisms or units as soon as the latter reach a predetermined maximum temperature.

One of the objects of my invention is to so construct such a control to be in series with an electrical circuit, that will act to break said circuit whenever the predetermined maximum temperature at the unit being controlled is reached, and which will not permit re-activating said circuit and control until the latter has been repaired or replaced.

Another object of the invention is to so construct a device of the kind described, that will insure that the fusible element of the same will drop away entirely from the rest of the electrical circuit of which it was a part originally, to thus positively cut off continued operation of said circuit until replacement or repair of the control unit has been had.

A further object of my invention is to so construct such a control, in which the fusible element will be encased within a housing provided with an enlarged pocket or reservoir that will comfortably receive and retain all of the melted or fused material and keep the latter spaced entirely away from the electrical circuit conductors, to insure that all current is cut olf positively in the latter.

Still further objects of the invention are to so construct a device of the kind described that the same will be relatively inexpensive to make, easy to install and service, will be suificiently strong and sturdy for its intended functions, will operate with certainty, is readily replaceable from time to time as needed, and which will be otherwise safe, satisfactory and efi'icient for use wherever deemed applicable.

Many other objects and advantages of the construction herein shown and described, and the uses and advantages obtained through use of this device, will be obvious to those skilled in the art to which this invention appertains, as will be apparent from the disclosures hereinafter given.

To this end, my invention consists in the novel construction, arrangement, combination and form herein shown and described, and the uses mentioned, as will be more clearly pointed out in the following specification.

In the drawings, wherein like reference characters represent like or corresponding parts throughout the views,

Figure 1 is an elevational view of an installation of the control;

Figure 2 is a horizontal cross-sectional detail of the control, mounted in place on the unit to be protected; and

Figure 3 is a vertical cross-sectional view, taken substantially along the line 33 of Fig. 2.

Referring more particularly to the drawings, wherein I have illustrated a preferred embodiment of my invention, A represents any type of mechanism or unit exnited States Patent 0 2,788,417 Patented Apr. 9, 1957 posed to high temperatures, as for example it may be a furnace of any kind or construction, say an oil-fed furnace, for instance.

B indicates the oil-feeder to the burner 1 of the furnace, and as desired, any number and kind of controls may be associated with one another in the system, for breaking the feed under certain conditions, as for example, a gas-valve control 2, a pilot thermostat 3, etc., these controls being in series as part of the electrical circuit leading from the power line 4-4, and intended to break the circuit through actuation of any one of said controls.

it happens however, that for one reason or another, as for example when foreign matter collects at the electrical contacts, or after one of the movable elements has been distorted accidentally or from tampering by inexperienced persons, the circuit is not broken when certain operating conditions have been reached, but upon the contrary will continue to operate and to keep feeding oil, gas or the like to the burner.

This not only wastes such fuel, and might damage one or more of the parts of the controls or of the furnace, piping, etc., but may even cause fire to be set to the entire premises in which the furnace is situated.

To avoid such danger, I have provided a separate unit to be installed in any part of the mechanism or unit that is subject to being heated, as for instance, the firebox, water-jacket, steam-pipes, stack, or in fact any area selected, and which is in the path of the heated medium, and which is arranged as a part of and in series with the electrical circuit, to break said circuit under certain predetermined conditions.

Such a control unit may include a tubular element 5 made of suitable heat-resistant material such as steel, bronze, etc., and which may have any number of perforations 6 through its side wall, if desired. An electrical conductor 7 is extended through this tube, and may be held in properly centered position to be spaced from the enclosing Wall of the tube, by porcelain or other suitable insulators 8, the free ends of said conductor having spring contacts 9-9 for frictional engagement with a pair of contacts 1010 carried by an element that may be attached to that part of the furnace or other unit to be controlled. The element 11 carrying said contacts 1010 may be detachably affixed to said unit in any suitable manner.

It may be noted that said element 11 may be wholly of insulating material, or may have suitable portions of the same, of such electrical insulation, for obvious reasons.

A fusible element 12 may be arranged within said tube as a part of the current-carrying electrical circuit through the tube, and may be selected from any metal or other substance capable of carrying current and which will melt or fuse at a predetermined temperature. This element 12 will be in the path of the heated medium ambient of itself.

It is extremely important that when said element melts, all of its material will drop entirely to one side of the conductors, to thereby insure that no current Will pass through the device until a replacement of the re-fused unit is made, and to this end, I have enlarged said tube immediately below said positioning of the element 12, somewhat as shown, as by bulging the tube side wall radially downwardly or outwardly to provide a pocket 13 of sufiicient capacity to receive all of the melted element 12 and hold the same entirely below the remainder of the bottom portion of the enclosing wall of the tube.

With such construction, there is a certainty that when the element melts into said pocket, none of such melted material will be left to form contact between the gap in the conductor left by the falling fusible element, nor

will any such material flow" towards the contacts 9-9 or 1010 to permit continued flow of current through the circuit.

After said control has broken the circuit, inspection is thereupon made to ascertain the cause for such break, repair or re-adju'strn'eiits made; and a replacement tube with a fresh element 12 therein, is repositioned.

Having thus described my invention, it is obvious that various immaterial modifications may be madein the same without departing from the spirit of the invention; hence I do not wish to be understood as limiting myself to the exact form, arrangement, construction and combination herein shown, or uses mentioned, except as limited by the statev or the art to which this invention appertains'; and by the claimsherein stated.

I claim:

1. For use with substantially permanentl closed heated unit that is fed from" a source of power that is controlled by an electrical circuit, a protective mechanism in series with said circuit and comprising a' tube adapted to be place" Within said unit so as to be" heated by the ambient heat within said unit, and a tusible element in said tube and forming a part of said circuit to break the latter at a predetermined maximum temperature of said ambient heat that is independent of heat generated by current throughs'aid fusible element to thus shut ofi said power to said unit, said tube having a reservoir associated therewith to receive the fused element and hold it spaced from said circuit.

2. An electrical circuit breaker comprising a tube adapted to be placed substantially entirely, within a heating unit so as to be in" the immediate pathof the heated medium and communicating with the latter, and having electrical conductors operably connectable with electrical leads of said circuit, said tube replaceably insertible within said heating unit from entirely outside the latter, an element entirely within said tube electrically connected in series with said conductors and meltable at a predetermined temperature of said heated medium that is inde pendent of heat generated by current through said fusible element to break electric flow through said conductors, and a reservoir in said tube to receive said melted element and space it from said conductors.

'3. A device of the kind set forth in claim 2, but further characterized in that said reservoir is bulged radially outwardly from said tube.

4. A device of the kind set forth in claim 2, but further characterized in that said reservoir is of suficient capacity to contain all of the fused element to hold it spaced entirely below said conductors and is bulged downwardly from the ends of said tube.

5. A device'a's" set forth in claim 1, but further characterized in that the part of said circuit that is in said tube is frictionally operably' connectable with an adjacent part of said circuit so that said tube and its contents may be detachably replaceable.

References Cited in the file of this patent UNITED STATES PATENTS 887,061 Bowen May 12, 1908 1,386,525 Oca-Balda et a1. Aug. 2, 1921 1,684,522 Sloan Sept. 18, 1928 1,781,786 Luse Nov. 18, 1930 1,798,860 Woodr'ufi Mar. 31, 1931 2,017,639 Triplett Oct. 15, 1935 2,560,138 Swain July 10, 1951 

